1. Field of the Invention
The invention relates to door structures, and particularly to mechanism for sequentially unlatching and latching plug doors, such door moving transversely inwardly and outwardly of the door opening in a wall and moving the doors longitudinally of the wall out of and into registry with the door opening.
2. The Prior Art
U.S. Pat. No. 3,990,184 to Luther L. Bollinger, Sr. discloses doors of the type in which the front end of the door track curves from an outwardly spaced portion parallel to the car side toward the car side near the front edge of the door opening, with the front portion of the door directly mounted on a track mounted carriage and the rear portion of the door mounted by means of a crank on a track mounted carriage for movement into and out of the door opening by rotation of the crank mounting shaft, longitudinally slidable means on the door for unlocking the door and rotating the door-mounting shaft between the flush and outboard portions, with the longitudinally slidable mechanism on the door connected to a manually actuated pinion driving gear box carried by a rack on the car side, whereby through movement of the gear box along the rack in selected directions the longitudinally movable means on the door is caused to rotate the door mounting shaft out of or into door closed position and the door is moved longitudinally of the car into and out of registry with the door opening in the side wall thereof. In this patent, operation of the door mounting shaft requires that under certain conditions, a pair of longitudinally movable bars on the door be moved in unison and that under other conditions individual bars be moved separately and provides a mechanism including a lever mounted on the shaft and operable thereby and a co-operating cam on the locking pin to disengage and engage the two longitudinally movable bars responsive to relative positions of the mounting shaft. The patented construction also relies solely on the maintenance of the operating mechanism in its selected position to maintain the mounting shaft in its selected door closed or door open position.